Perhaps the most common impediment to wearer comfort and visual acuity of contact lenses is the presence of contaminants on the surface of the lens. The large majority of these contaminants are proteins produced by the eye, tear duct, and eyelid for lubrication and protection of delicate optic tissues. The proteins will agglomerate on the surfaces and the interior of the lens to form microscopic protrusions which rub against the cornea and eyelid, thereby causing irritation, inflammation, and discomfort.
There are a number of known methods for removing protein contaminants from a contact lens surface. Some removal systems use a mild detergent to wash the agglomerated proteins from the lens surface; however, these detergents can damage the lens. Others utilize a solution containing a proteolytic enzyme which digests the protein molecules, but this method has proven inadequate for complete protein removal.
One recently conceived solution for removal of protein from contact lenses is the application of electrophoresis techniques. Cowle et al., U.S. Pat. No. 4,921,544. discloses a method wherein the contact lens is placed in an electrophoretic solution within a container, then an electric field is applied to the solution through two electrodes in the solution which causes charged protein molecules attached to the lens to migrate to the oppositely charged electrode. Although the application of electrophoresis to the cleaning of lenses is promising, any protein migrating to an electrode must also overcome a diffusion gradient created by the migration which tends to drive protein from the electrode into solution. An equilibrium is eventually reached, at which point it becomes difficult to further remove protein from the solution at the electrode; some of this free protein then is able to return to the lens.
Another electrochemical solution is offered in Pankow, U.S. Pat. No. 4,872,965. In this method, electrodes are immersed in solution baths external to the lens; current is provided to the lens by a transmission means which rests on the lens surface. Application of electrical current causes contaminants to migrate from the center of the lens to its surface. From this point the contaminants are removed from either the lens surface or from the electrochemical transmission means by an additional wiping step.
Accordingly, it is an object of the present invention to provide an electroblotting method of cleaning contact lenses which overcomes the problem associated with the equilibrium of electrochemical and diffusion gradients. It is a further object of the present invention to provide an electroblotting method of cleaning contact lenses which eliminates the need for wiping protein from the lens after the application of electric current. It is an additional object of the invention to do so with a simple, inexpensive, and easily used method suitable for commercial production.